Our analysis revealed a notable trend in ADHD dispensing rates following the implementation of the Youth Act in 2015. Initially, prevalence rates increased significantly from 39.2 per thousand youths in 2010 to a peak of 45.7 per thousand youths in 2015. However, after 2015, there was a steady decline in prevalence rates, reaching the lowest number of users by 2022 at 35.2 per thousand youths. Additionally, we found that males were dispensed ADHD medication more frequently than females, with notably higher prevalence rates, particularly in the age groups of 7–12 years and 13–19 years. However, males in these age groups also experienced the most significant decline in prevalence rates after 2015. Furthermore, males had longer durations of treatment compared to females. In contrast, females aged 13–19 years showed a significant increase in incidence rates, rising from 3.5 per thousand in 2015 to 5.3 per thousand by 2022. Among the various ADHD medications, methylphenidate was the most dispensed drug (86.6%) during the study period, followed by dexamphetamine (9.0%), atomoxetine (2.3%), and lisdexamfetamine (1.2%). The prevalence rates of all ADHD medications declined after the implementation of the Youth Act, except for lisdexamfetamine where an increase in prevalence rates was observed after 2018.

Consistent with earlier findings in adults between 2004 and 2014 [15], methylphenidate was the most dispensed ADHD drug in our findings. Another study illustrated an increase in methylphenidate use in youths from 2003 until 2013, followed by a stabilization in subsequent periods [16]. Our data on youths aligns with this trend, showing an increase from 31.7 per thousand youths in 2010 to the highest prevalence rate of 35.4 per thousand youths in 2013. The following years up to 2022 demonstrated a sustained decrease, reaching the lowest prevalence of 25.0 per thousand youths in 2022. Moreover, the Dutch Foundation for Pharmaceutical Key Figures (Stichting Farmaceutische Kerngetallen) reported a decrease in methylphenidate usage among individuals under 18 years old between 2017 and 2021 [17]. This reduction was observed across all age groups and both sexes in our findings, indicating a declining trend in the prevalence of ADHD medication dispensing after the implementation of the Youth Act in 2015. Besides the decline in methylphenidate dispensing after 2015, our findings indicate a noticeable shift towards other ADHD medications. The decrease in the methylphenidate dispensing prevalence and the concurrent increase in the prevalence rates of dexamphetamine, lisdexamfetamine, and atomoxetine dispensing suggest that patients may be switching between these medications. Additionally, the prevalence of dexamphetamine dispensing decreased from 4.4 per thousand youths in 2015 to 3.5 per thousand youths in 2017, followed by a brief increase and subsequent decrease to 3.2 per thousand youths in 2020, which may be associated with the increasing prevalence of lisdexamfetamine dispensing. Lisdexamfetamine was officially registered in 2018, marking the beginning of its gradual increase in dispensing, which peaked at a prevalence of 2 per thousand youths in 2022. The rapid rise suggests that individuals may have switched from dexamphetamine to lisdexamfetamine due to its beneficial pharmacokinetic profile, which leads to a longer duration of activity [18]. The dispensing data indicate that youths initially received methylphenidate, followed by dexamphetamine, and subsequently lisdexamfetamine, atomoxetine, or guanfacine. This aligns with the steps described in the treatment approach according to the Dutch guidelines [2]. It is important to recognize that these guidelines are used as guidance for prescribers, and treatments are optimized and personalized for each patient. This variability in treatment approach could also explain the absence of a drastic decrease in overall medication use among youth (39.2 per thousand youths in 2010, compared to 35.2 per thousand youths in 2022), as the severity of ADHD symptoms among individuals in the study population may vary significantly.

Besides the implementation of the Youth Act, there have been other factors between 2010 and 2022 that could have played a role in the use of ADHD medication among youths. Firstly, lower prevalence rates among children aged 0–6 years align with the current Dutch treatment guidelines, as ADHD medications are not approved for children under 6 years [2]. In some cases, however, a specialist may decide to prescribe off-label. Nevertheless, our results indicate a significant decrease in dispensations from 4.4 per thousand youths in 2010 to 1.3 per thousand youths in 2022 (p < 0.001) for children aged 0 to 6 years. Secondly, the DSM-5 was published in 2013, with subtle yet significant changes to diagnostic criteria and treatment approaches for ADHD compared to the DSM-IV [19]. Notably, in the DSM-5, the age range broadened for symptom onset to before 12, potentially leading to more children and adolescents meeting diagnostic criteria for ADHD. Additionally, the symptom threshold was reduced from at least six symptoms to five for adolescents and adults, recognizing that symptoms may decrease with age. Furthermore, the DSM-5 emphasized the assessment and diagnosis of comorbid conditions alongside ADHD, such as anxiety, depression, and learning disabilities, which may lead to increased polypharmacy in treatment regimens. Our study observed the use of concurrent medication among youths receiving ADHD medications, which aligned with existing literature on co-medication use in children with ADHD [3]. Our findings revealed that 18.1% of participants were dispensed antidepressants, such as SSRIs or TCAs, alongside ADHD medication, and 6.8% were dispensed anxiolytic benzodiazepines. The dispensations of these co-medications underscore the prevalence of co-morbid mental health disorders, such as depression and anxiety, among children and adolescents with ADHD [4]. Thirdly, the potential impact of the coronavirus disease 2019 (COVID-19) pandemic and subsequent school closures and home schooling on ADHD medication dispensing patterns remains unclear. Gimbach et al. observed a rise in ADHD prescriptions across Europe, including the Netherlands [20]. However, our data—focused specifically on Dutch youth aged 0–19—show a decline in dispensing between 2019 and 2022. This contrast may reflect age-specific responses to the pandemic. Among adults, increased mental health awareness and routine disruptions may have contributed to more diagnoses and treatment. In children, by contrast, school closures and reduced access to diagnostic services likely resulted in fewer new cases and temporary discontinuation of medication during remote learning. Additionally, structural factors such as the Youth Act may have created barriers to care for youth, including longer waiting times and administrative hurdles. Gangapersad et al. reported a moderate increase in antipsychotic medication use among youth up to 19 years old during the COVID-19 pandemic [21], suggesting broader changes in pediatric psychotropic dispensing. Additional research is required to clarify the specific effects of COVID-19 on ADHD medication usage in Dutch youth.

Lastly, medication shortages have posed a substantial problem in the Netherlands during the last two years of our study period. According to the Royal Dutch Society for the Promotion of Pharmacy (KNMP), there were 1,514 drug shortages in 2022, including key ADHD medications such as methylphenidate, lisdexamfetamine, and atomoxetine [22]. These shortages may have influenced dispensing trends in 2021 and 2022. KNMP Farmanco, the national medication shortage monitoring system, provided only general timeframes of medication unavailability but lacked detailed data on stock levels, shortage severity, causes, and substitution practices. Although switching to alternative brands was often possible, delays or reluctance to switch may have affected medication use. Due to these data limitations, we were unable to quantify the exact impact of the shortages.

Regarding differences between sexes, our findings showed a significant increase in ADHD medications incidence rates among female adolescents (3.5 per thousand females in 2015 vs. 5.3 per thousand in 2022, p < 0.001). This development aligns with literature highlighting the growing awareness of ADHD among marginalized populations, such as females and older individuals [23, 24]. Females often receive an ADHD diagnosis later than males, likely due to differences in symptom manifestation. Males with ADHD typically show externalized symptoms, such as hyperactivity and impulsivity, while females tend to show internalized symptoms [25, 26]. Studies in Finland and France have also reported increased ADHD medication use among older individuals [27, 28]. For instance, in France, adults represented 34% of incident methylphenidate users. Additionally, we found that females had slightly shorter durations of ADHD medication use compared to males (see appendix II). This could be attributed to under-identification and/or absence of symptoms, and differences in coping strategies, resulting in a perceived lesser need for medication [29].

The findings of this study should be interpreted considering its limitations. Firstly, as this was an exploratory study, we conducted multiple chi-square tests without applying corrections for multiple comparisons. While this approach can increase the likelihood of Type I errors, it is appropriate for identifying potential patterns and generating hypotheses for future research. Accordingly, the findings should be viewed as preliminary and interpreted with appropriate caution.

Secondly, the database provides data from pharmacies in various regions of The Netherlands, but the exact locations of the pharmacies are not known. A study conducted in Germany observed lower ADHD medication user rates in rural regions compared to urban areas [30]. Differences in healthcare access between rural and urban regions might potentially influence dispensing patterns. However, IADB.nl database has been proven to be representative for the entire Netherlands [12].

Additionally, the Youth Act, implemented in 2015, decentralized youth mental health services from the national to municipal governments. Although it did not formally alter diagnostic or treatment thresholds, it aimed to promote integrated and preventative care. In practice, this led to variability in service organization, administrative procedures, and access to specialized care across municipalities. Implementation was neither uniform nor immediate across all municipalities, as each local government had discretion over how and when to organize services. This resulted in regional differences in timing and approach, potentially influencing observed medication rates, particularly in the years immediately following the reform. While our data, drawn primarily from the northern and eastern Netherlands, are representative, they do not allow for detailed analysis of regional disparities.

Another limitation concerns the definition for new users that was applied in this research. A new user was defined as an individual with a 90-day period without drug dispensing prior to starting a treatment. This categorization may have led to episodic ADHD medication users being classified as new users, potentially resulting in an overestimation of incidence rates. Furthermore, the duration of use may have been underestimated, and incidence rates might be overestimated due to the absence of information on dispensing during hospitalization and in-hospital medication use. Additionally, the exact age of individuals in the IADB.nl database is not known, as the database only provides dates of birth as January 1st or July 1st of the corresponding year. Consequently, when calculating ages, patients could exceed 19 years by several months. Therefore, only individuals up to the calculated age of 18.5 years were included to adhere to the age criteria of 0–19 years.

Finally, it is important to highlight that information on treatment adherence and exact indication is unavailable, and no details are available on the exact formulation of the drugs. Due to this limitation, the obtained dispensing data may not accurately reflect actual ADHD medication use with certainty. Additionally, literature reports instances of improper use of ADHD medication among students in The Netherlands [31]. This implies that the dispensations included in this study could have been distributed and not solely used for their intended treatment purposes. It is plausible that additional ADHD medication users exist but are not documented in our database. However, it is noteworthy that individuals engaging in improper use are typically not formally diagnosed with ADHD and have not obtained prescribed medication. Consequently, they would not be included in the database.